Shock Strut Percolation Aperture for Gas-Free Damping Chambers

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Solution Overview

Problem

Shock struts with mixed air/oil chambers face inefficiency due to gas leakage into the dynamic liquid damping chamber when retracted, which can hinder performance during landing events as gas remains in the lower chamber, reducing operational efficiency.

Innovation Solution

Incorporating a percolation tube between the first and second chambers, with a percolation aperture that allows gas to move from the first to the second chamber as the shock strut transitions from retracted to deployed positions, enhancing fluid flow and gas evacuation through the main metering orifice, ensuring the lower chamber is gas-free for optimal performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a metering orifice is used to separate the dynamic liquid damping chamber from the mixed air/oil chamber, then damping control is achieved, but gas leaks into the dynamic liquid damping chamber when retracted, reducing operational efficiency

Engineering Contradiction:
Improveoperational efficiencyVSAvoidgas leakage into dynamic liquid damping chamber
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The orifice plate is segmented into multiple functional apertures: a metering pin aperture for controlled liquid damping and a percolation aperture for gas evacuation. This segmentation allows the plate to simultaneously perform metering and gas separation functions, preventing gas contamination in the dynamic liquid damping chamber while maintaining damping control.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The percolation aperture acts as an intermediary pathway that facilitates gas movement from the mixed air/oil chamber to the upper chamber. This intermediate gas evacuation route prevents direct gas leakage into the dynamic liquid damping chamber, resolving the harmful gas contamination effect while preserving the metering orifice's damping function.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Object-generated harmful factors

If the percolation aperture cross-sectional area is made smaller than the metering area, then gas evacuation is enabled without compromising liquid damping performance

Engineering Contradiction:
Improvegas evacuation efficiencyVSAvoidliquid damping performance
Core Design Contradiction:
Object-generated harmful factorsVSProductivity

Solution Approach 1:

Different apertures in the orifice plate are assigned different cross-sectional areas based on their specific functions. The percolation aperture has a smaller area optimized for gas evacuation, while the metering pin aperture maintains a larger area for liquid damping. This local differentiation of aperture sizes allows each to perform its function optimally without compromising the other.

Inventive Principle:
Principle #3Local quality

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This configuration ensures the dynamic liquid chamber is quickly filled with liquid and gas is efficiently evacuated, maintaining the shock strut's efficiency by ensuring the lower chamber is devoid of gas during critical events, thereby enhancing operational performance.

Implementation Method 1

The percolation aperture is configured to allow a gas to move from a first chamber to a second chamber in response to the shock strut moving from a retracted position to a deployed position

Methodology Applied
Scientific EffectPressure gradient: Pressure Gradient

Implementation Method 2

Shock struts with mixed air/oil chambers may typically have a dynamic liquid damping chamber separated from a mixed air/oil chamber by a metering orifice

Methodology Applied
Scientific EffectViscous damping: Viscous Damping

Data Source

PatentEP3505788B1Shock strut percolation
Publication Date: 2024.02.28 GOODRICH CORP
  • EP3505788B1 patent drawingFigure 1
  • EP3505788B1 patent drawingFigure 2A~2B
  • EP3505788B1 patent drawingFigure 3A~3B

AI summary

A shock strut may comprise an orifice plate (230) comprising a metering pin aperture (232) and a percolation aperture (234). The percolation aperture (234) may be configured to allow a gas to move from a first chamber to a second chamber in response to the shock strut moving from a retracted position to a deployed position.